Gunn effect in CdTe

We have been examining the response of n-type CdTe to pulsed electric fields. In our best units, prepared to have a uniform cross section, the current remains ohmic, to good approximation, almost to threshold. Above the threshold field of (13±2) kV/cm well-defined Gunn oscillations are observed with a spike amplitude 35-50 percent of the total current. We estimate a domain drift velocityv_{dd}=7times10^{6}cm/s, a field outside the domainE_{1} = 7kV/cm, and a domain fieldE_{2}gsim37kV/cm. After a few nanoseconds of operation, however, current runaway occurs in units showing the spiking mode of oscillation, presumably because of carrier ionization induced by the moving high-field domains.     

Gunn effect bibliography

In view of the rapidly expanding interest and activity in the area of the Gunn effect, the following bibliography has been compiled for people who are studying or doing research in this area. The term "Gunn effect" is used, in general, to collectively describe a number of classes of bulk negative resistance behavior in semiconductors with energy band structures like that of GaAs. These modes of behavior include small-signal amplification, pure accumulation of space charge, mature dipole (true Gunn effect) mode. quenched accumulation (LSA) mode, and quenched dipole mode. These references deal with the theory, experimental results, and applications of the Gunn effect. Works of a fundamental nature concerning phenomena that are basic to all semiconductor behavior and other bulk negative resistance effects have not been included. Also, basic papers dealing with electron transport phenomena, such as hot electron theory and intervalley scattering, which are essential to a complete understanding of the Gunn effect and articles on the properties and band structure of GaAs, InP, CdTe, and other III-V compounds have not generally been included, although in certain cases they are listed if they have been frequently cited. As in the compilation of any bibliography, it is self-evident that some valuable and pertinent articles may have been overlooked.     

The Gunn effect

The research that led up to the discovery of the Gunn effect is described by the author. A brief explanation of the effect is given, and the present use of Gunn diodes is also indicated     

Delay structures with planar Gunn devices

A pulse delay obtained with the aid of the domain travelling effect in Gunn devices is described. For this purpose, the planar Gunn devices contain, in addition to a trigger electrode, a capacitive electrode for coupling out the signal. Experimental results are given for the single component and a monolithic integrated cascade circuit. The devices are appropriate for constructing dynamic shift registers in the sub-nanosecond range.     

Stabilisation of Gunn oscillations in layered semiconductor structures

2-stream interaction between an active GaAs diode and a passive biased semiconductor is shown to reduce the growth rate of a space-charge wave by a factor proportional to the difference of carrier drift velocities in the two interacting semiconductors. This mechanism offers a possible way for stabilising Gunn oscillators with large n0L products.     

Gunn effect bibliography supplement

This list of references has been prepared as a supplement to our "Gunn Effect Bibliography," which appeared in this Transactions, vol. ED-15, pp. 777-788, October 1968. These references represent 1968 articles that have been published since the original bibliography was submitted, as well as additional earlier articles.     

YIG-tuned Gunn effect oscillator

A mechanical cavity of coaxial or waveguide type is generally used as a resonator of a Gunn oscillator. Reported here is the use of a resonator consisting of a ferrimagnetic sample instead of the mechanical cavity to obtain the electrically tunable Gun oscillator. The coupling between the Gunn diode and the the ferrimagnetic resonator was experimentally observed and oscillation frequency from 3.2 GHz to 2.4 GHz was obtained proportionally to the applied dc magnetic field.     

Domain stability in the Gunn effect

The present theoretical and experimental knowledge of the high-field domain in the Gunn effect gives conflicting result. The letter shows that these can be reconciled by a modification to the published reasoning about domain formation.     

The Gunn effect in polar semiconductors

The main features of the Gunn effect can be accounted for by the transferred electron model of Ridley and Watkins, which predicts a bulk differential negative resistance and subsequent domain formation if electrons can be transferred sufficiently rapidly from the lowest conduction-band minimum to lower-mobility subsidiary minima. Experimental results forn-GaAs in verification of such a bulk negative resistance are presented. In the longer samples the current-time waveform consists of sharp spikes separated by flat valleys, as expected from the motion of domains. The voltage across the domains is found to scale with sample length as predicted; the value of the electric field inside the domain is estimated to be ≥60 000 V/cm, while the field outside is about 1500 V/cm. Gunn effect oscillations have also been observed inn-CdTe, but not inn-InSb orn-InAs. The absence of an instability in InSb and InAs is consistent with the transferred electron model, since the subsidiary minima in these materials are believed to be too high in energy to be populated before carrier multiplication occurs. Finally, it will be shown that unless the separation of the conduction-band minima is very small, the critical electric field at which the Gunn effect occurs is reasonably well predicted by the one-band polar optical mode runaway field.     

Carrier generation-recombination in the Gunn effect

It is conventional to assume that the Gunn Instability develops on a time scale fast compared with the carrier generation-recombination processes. This enables one to account for the motion of Gunn Domains by means of a phenomenological model in which the impurity ionization remains at its thermal equilibrium value. The standard Gunn Effect model has been modified to include the space-time dependent impurity ionization expected if the carrier generation-recombination processes become important.A dispersion relation describing the linear response of the system to small perturbations for the case of field dependent recombination has been derived and used to deduce a simple stability criterion. The time evolution of the electric field when this condition is violated has been studied via a numerical solution of the phenomenological equations. Under appropriate conditions both fast and slow moving instabilities have been found to occur.     

Gunn effect swept frequency oscillator

An X-band swept frequency oscillator using a Gunn diode and a ferrite phase shifter is described. Sweep widths of 800 MHz and sweep rates up to 400 Hz with less than 3 dB power variation have been obtained.     

Ferrimagnetically tunable Gunn effect oscillator

A very wide frequency tuning (5.8 to 13.0 GHz) of the Gunn effect oscillator is described, in which the properties of the ferrimagnetic resonator sphere are used as a tuning element. The circuit employed to accomplish this tuning, the power profile, and the tuning curve are also presented.     

Gunn effect with two samples in parallel

The current waveform of two long Gunn oscillators in parallel in a transmission line is described and is extended to include the effect of putting a resistor in series.     

Gallium arsenide on sapphire Gunn effect devices

The epitaxial growth of single-crystal GaAs on an insulating sapphire substrate, recently reported, has been used in the fabrication of Gunn effect devices.     

Nonuniform motion of high-field domains in the Gunn effect

In recent publications, rules have been established for obtaining the properties of the high-field domain traversing in a steady state across Gunn diodes. This letter shows that these steady-state properties cannot be reconciled with the formation stage of the domain without some extension of the theory to include the non-steady-state domain. This letter provides the necessary extension of these rules and concludes with a qualitative account of the domain dynamics from the formation stage up to equilibrium.     

Suppression of Gunn oscillations by a two-dimensional effect

Suppression of Gunn oscillations in thin-film Gunn diodes by a two-dimensional effect is described theoretically and experimentally. Experiments show that Gunn oscillations do not occur in diodes whose nt product is less than 1.1 × 10¹¹(cm^-2), where t is the film thickness. This stabilized sample is useful for amplifiers.     

基于耿氏效应的太赫兹器件的研究进展

介绍基于耿氏效应的器件在太赫兹领域的研究,详细地阐述耿氏二级管的原理、工艺流程、关键技术的解决和耿氏二极管频率和功率的提高等.重点介绍耿氏二极管的封装工艺和耿氏二极管腔体的具体结构.系统论述通过制备腔体需要的关键尺寸,如腔体内部尺寸、波导型号,从而提取基波与谐波,并提出其提高频率和功率的途径.